1 /* libFLAC - Free Lossless Audio Codec library 2 * Copyright (C) 2006,2007 Josh Coalson 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 7 * 8 * - Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 11 * - Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * - Neither the name of the Xiph.org Foundation nor the names of its 16 * contributors may be used to endorse or promote products derived from 17 * this software without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 21 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 22 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR 23 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 24 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 25 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR 26 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF 27 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING 28 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS 29 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 30 */ 31 32 #if HAVE_CONFIG_H 33 # include <config.h> 34 #endif 35 36 #include <math.h> 37 #include "FLAC/assert.h" 38 #include "FLAC/format.h" 39 #include "private/window.h" 40 41 #ifndef FLAC__INTEGER_ONLY_LIBRARY 42 43 #ifndef M_PI 44 /* math.h in VC++ doesn't seem to have this (how Microsoft is that?) */ 45 #define M_PI 3.14159265358979323846 46 #endif 47 48 49 void FLAC__window_bartlett(FLAC__real *window, const FLAC__int32 L) 50 { 51 const FLAC__int32 N = L - 1; 52 FLAC__int32 n; 53 54 if (L & 1) { 55 for (n = 0; n <= N/2; n++) 56 window[n] = 2.0f * n / (float)N; 57 for (; n <= N; n++) 58 window[n] = 2.0f - 2.0f * n / (float)N; 59 } 60 else { 61 for (n = 0; n <= L/2-1; n++) 62 window[n] = 2.0f * n / (float)N; 63 for (; n <= N; n++) 64 window[n] = 2.0f - 2.0f * (N-n) / (float)N; 65 } 66 } 67 68 void FLAC__window_bartlett_hann(FLAC__real *window, const FLAC__int32 L) 69 { 70 const FLAC__int32 N = L - 1; 71 FLAC__int32 n; 72 73 for (n = 0; n < L; n++) 74 window[n] = (FLAC__real)(0.62f - 0.48f * fabs((float)n/(float)N+0.5f) + 0.38f * cos(2.0f * M_PI * ((float)n/(float)N+0.5f))); 75 } 76 77 void FLAC__window_blackman(FLAC__real *window, const FLAC__int32 L) 78 { 79 const FLAC__int32 N = L - 1; 80 FLAC__int32 n; 81 82 for (n = 0; n < L; n++) 83 window[n] = (FLAC__real)(0.42f - 0.5f * cos(2.0f * M_PI * n / N) + 0.08f * cos(4.0f * M_PI * n / N)); 84 } 85 86 /* 4-term -92dB side-lobe */ 87 void FLAC__window_blackman_harris_4term_92db_sidelobe(FLAC__real *window, const FLAC__int32 L) 88 { 89 const FLAC__int32 N = L - 1; 90 FLAC__int32 n; 91 92 for (n = 0; n <= N; n++) 93 window[n] = (FLAC__real)(0.35875f - 0.48829f * cos(2.0f * M_PI * n / N) + 0.14128f * cos(4.0f * M_PI * n / N) - 0.01168f * cos(6.0f * M_PI * n / N)); 94 } 95 96 void FLAC__window_connes(FLAC__real *window, const FLAC__int32 L) 97 { 98 const FLAC__int32 N = L - 1; 99 const double N2 = (double)N / 2.; 100 FLAC__int32 n; 101 102 for (n = 0; n <= N; n++) { 103 double k = ((double)n - N2) / N2; 104 k = 1.0f - k * k; 105 window[n] = (FLAC__real)(k * k); 106 } 107 } 108 109 void FLAC__window_flattop(FLAC__real *window, const FLAC__int32 L) 110 { 111 const FLAC__int32 N = L - 1; 112 FLAC__int32 n; 113 114 for (n = 0; n < L; n++) 115 window[n] = (FLAC__real)(1.0f - 1.93f * cos(2.0f * M_PI * n / N) + 1.29f * cos(4.0f * M_PI * n / N) - 0.388f * cos(6.0f * M_PI * n / N) + 0.0322f * cos(8.0f * M_PI * n / N)); 116 } 117 118 void FLAC__window_gauss(FLAC__real *window, const FLAC__int32 L, const FLAC__real stddev) 119 { 120 const FLAC__int32 N = L - 1; 121 const double N2 = (double)N / 2.; 122 FLAC__int32 n; 123 124 for (n = 0; n <= N; n++) { 125 const double k = ((double)n - N2) / (stddev * N2); 126 window[n] = (FLAC__real)exp(-0.5f * k * k); 127 } 128 } 129 130 void FLAC__window_hamming(FLAC__real *window, const FLAC__int32 L) 131 { 132 const FLAC__int32 N = L - 1; 133 FLAC__int32 n; 134 135 for (n = 0; n < L; n++) 136 window[n] = (FLAC__real)(0.54f - 0.46f * cos(2.0f * M_PI * n / N)); 137 } 138 139 void FLAC__window_hann(FLAC__real *window, const FLAC__int32 L) 140 { 141 const FLAC__int32 N = L - 1; 142 FLAC__int32 n; 143 144 for (n = 0; n < L; n++) 145 window[n] = (FLAC__real)(0.5f - 0.5f * cos(2.0f * M_PI * n / N)); 146 } 147 148 void FLAC__window_kaiser_bessel(FLAC__real *window, const FLAC__int32 L) 149 { 150 const FLAC__int32 N = L - 1; 151 FLAC__int32 n; 152 153 for (n = 0; n < L; n++) 154 window[n] = (FLAC__real)(0.402f - 0.498f * cos(2.0f * M_PI * n / N) + 0.098f * cos(4.0f * M_PI * n / N) - 0.001f * cos(6.0f * M_PI * n / N)); 155 } 156 157 void FLAC__window_nuttall(FLAC__real *window, const FLAC__int32 L) 158 { 159 const FLAC__int32 N = L - 1; 160 FLAC__int32 n; 161 162 for (n = 0; n < L; n++) 163 window[n] = (FLAC__real)(0.3635819f - 0.4891775f*cos(2.0f*M_PI*n/N) + 0.1365995f*cos(4.0f*M_PI*n/N) - 0.0106411f*cos(6.0f*M_PI*n/N)); 164 } 165 166 void FLAC__window_rectangle(FLAC__real *window, const FLAC__int32 L) 167 { 168 FLAC__int32 n; 169 170 for (n = 0; n < L; n++) 171 window[n] = 1.0f; 172 } 173 174 void FLAC__window_triangle(FLAC__real *window, const FLAC__int32 L) 175 { 176 FLAC__int32 n; 177 178 if (L & 1) { 179 for (n = 1; n <= L+1/2; n++) 180 window[n-1] = 2.0f * n / ((float)L + 1.0f); 181 for (; n <= L; n++) 182 window[n-1] = - (float)(2 * (L - n + 1)) / ((float)L + 1.0f); 183 } 184 else { 185 for (n = 1; n <= L/2; n++) 186 window[n-1] = 2.0f * n / (float)L; 187 for (; n <= L; n++) 188 window[n-1] = ((float)(2 * (L - n)) + 1.0f) / (float)L; 189 } 190 } 191 192 void FLAC__window_tukey(FLAC__real *window, const FLAC__int32 L, const FLAC__real p) 193 { 194 if (p <= 0.0) 195 FLAC__window_rectangle(window, L); 196 else if (p >= 1.0) 197 FLAC__window_hann(window, L); 198 else { 199 const FLAC__int32 Np = (FLAC__int32)(p / 2.0f * L) - 1; 200 FLAC__int32 n; 201 /* start with rectangle... */ 202 FLAC__window_rectangle(window, L); 203 /* ...replace ends with hann */ 204 if (Np > 0) { 205 for (n = 0; n <= Np; n++) { 206 window[n] = (FLAC__real)(0.5f - 0.5f * cos(M_PI * n / Np)); 207 window[L-Np-1+n] = (FLAC__real)(0.5f - 0.5f * cos(M_PI * (n+Np) / Np)); 208 } 209 } 210 } 211 } 212 213 void FLAC__window_welch(FLAC__real *window, const FLAC__int32 L) 214 { 215 const FLAC__int32 N = L - 1; 216 const double N2 = (double)N / 2.; 217 FLAC__int32 n; 218 219 for (n = 0; n <= N; n++) { 220 const double k = ((double)n - N2) / N2; 221 window[n] = (FLAC__real)(1.0f - k * k); 222 } 223 } 224 225 #endif /* !defined FLAC__INTEGER_ONLY_LIBRARY */ 226
